Various sensors are known in the pressure sensing arts. Pressure sensors are commonly used in a wide variety of commercial and industrial applications. Such devices are employed because of their wide range pressure sensor operating applications and ability to operate in a variety of different environments. The pressure sensor operating environment, however, may place various operational constraints on the pressure sensor and its internal components
Electrical contacts, otherwise referred to as terminals or contact pins, are used in the electronics industry in conjunction with PCB's (Printed Circuit Boards), electrical panels, connector cables and other devices, for making electrical connections to and from pressure sensors. As used herein, the terms “electrical” and “electronic”, and conjugations thereof, are synonymous and interchangeable, and refer to any component, circuit, device or system, which utilizes the principles of electricity in its operation.
Compliant pins can include press-fit portions, which have certain elasticity. Such compliant pins are press-fitted into through-holes in a circuit board that possesses inner diameters slightly smaller than the outer diameters of the press-fit portions. When the pins are press-fitted into the through-holes, the press-fit portions closely contact (i.e., pressure contact) plated interior surfaces of the through-holes, while flexing in a direction perpendicular to an axial direction of the compliant pins. The compliant pins are then fixed to the circuit boards, and favorable electrical connections can be established between the compliant pins and circuits of the circuit board without soldering the contact portions therebetween. It is because situations occur in which forces are applied to the compliant pins in a direction of extraction that it is desirable that the contact pressure generated between the compliant pins and the through-holes be approximately 10 Newtons or greater in order to maintain an electrically stable connection. Such forces may be applied, for example, during the mounting and removal of electrical connectors or due to external factors.
Referring to FIG. 1, a side elevational view of a prior art compliant-based apparatus 100 is disclosed. A solid compliant connector contact 100 includes a guide portion 102, a contact portion 108, a first tapered portion 106 and a second tapered portion 110, all located generally adjacent one end of the contact. The first tapered portion 106 is disposed between the guide portion 102 and the contact portion 108 to facilitate movement of the contact portion into a hole (H) in a circuit board (CB).
The contact portion 108 and small parts of the tapered portions 106, 110 are formed to be compliant for holding the contact in electrical contact with the circuit board in the hole. The second tapered portion 110 is on the opposite (left) side of the contact portion 108 from the first tapered portion 106 and transitions to a mid-section 112 of the connector contact 100 having a larger diameter than the guide portion 102 for greater current carrying capacity and mechanical strength. The end of the contact 100 opposite the guide portion 102 is formed as a female connection portion (generally indicated at 118) having an axial socket 114 and slits 116 on diametrically opposite sides of the contact extending into the socket.
One of the problems with the prior art apparatus 100 is that compliant pins are used in electrical components, such as electrical connectors. When an electrical component is mounted onto a circuit board, the compliant pins simultaneously fix the electrical component to the circuit board and establish electrical connections between the electrical component and the circuit board. The prior art apparatus 100 does not adequately meet such requirements. Accordingly, it is desirable for the press-fit portions of the compliant pins to have a large holding force over long periods of time, which is a feature not adequately served by the prior art apparatus 100. It is also desirable that the force required to insert the compliant pins into the circuit board be low to facilitate mounting of the electrical component onto the circuit board. Because the compliant pins are formed from high strength materials and the press-fit portions are structured to generate great contact pressure with slight displacement, the circuit board must be formed from thick high strength materials in order to be able to withstand the contact pressure applied by the compliant pins. The diameters of the through-holes in the circuit boards are therefore limited to a narrow range, which is an additional problem encountered with the prior art apparatus 100.
Some pressure sensors use ceramics or printed circuit boards (PCB) to hold pressure sensing elements inside a package. This substrate needs to be connected to a leadframe for external connection. This connection is typically accomplished via soldering or wire bonding. These processes are expensive, difficult and a concern for failures in user applications.
Accordingly, a need exists for a new compliant pin in pressure sensor that relies on a force connection and does not require solder or wire bonding, and which overcomes the problems associated with the prior art apparatus 100.